Improvement of luminescence properties in Zn2.1Mg0.9Ta2O8:Cr3+ by the cation substitution and its application in biological nondestructive testing and night vision lighting.

Recently, it is of great significance to explore near-infrared (NIR) phosphor with more application prospects. In this work, a series of Zn2.1 Mg(0.9 - y)GaySnyTa(2 - y)O8:0.003Cr3+ NIR broadband phosphors with high quantum yields and high thermal stability are discovered by uniquely replacing [Mg2+-Ta5+] in Zn2.1Mg0.9Ta2O8 with [Ga3+-Sn4+]. Under 460 nm excitation, Zn2.1Mg0.85Ga0.05Sn0.05Ta1.95O8: 0.003Cr3+ depicts the 600-1100 nm broadband emission with a full-width at half maximum (FWHM) of 210 nm, and the quantum yields can reach 61.2%. Finally, the phosphor was mixed with epoxy resin and encapsulated in a 460 nm blue light emitting diode (LED) chip to convert the NIR LED by phosphor (NIR pc-LED), which was applied in the field of biological nondestructive testing and night vision lighting.

High-Quantum-Efficiency Blue Phosphors with Superior Thermal Stability Derived from Eu3+-Doped Faujasite Y Zeolite.

Blue phosphors of high efficiency and superior thermal stability constitute the critical component for achieving high-quality white light-emitting diodes (WLEDs). Herein, we report a highly efficient blue-emitting phosphor with superior thermal stability by heating Eu3+-doped Faujasite Y zeolite under a reducing atmosphere. The intensity and peak value of the phosphor are highly dependent on calcination temperature, and the intensity of PLE and PL spectra reaches a maximum at 1100 °C. Under the excitation of 360 nm, the phosphor shows a high quantum efficiency (90%) and thermal stability (the emission intensity at 423 K is about 125% of that at room temperature). WLEDs fabricated using this blue phosphor, a yellow Eu2+-SOD phosphor, and a commercially available red Sr2Si5N8:Eu2+ phosphor exhibit an excellent optical performance with a correlated color temperature of 4359 K and a color rendering index of 97. This work provides a new strategy for the synthesis of phosphors with high thermal stability and luminous efficiency.

Tb3+-based multi-mode optical ratiometric thermometry.

Owing to some special superiority, luminescence ratiometric thermometry, mainly including dual excitations single emission and single excitation dual emissions, has gained popularity over the past few years. However, developing novel ratiometric thermometry that can work in multi-mode is still a challenge. Here we report a temperature measurement method based on the photoinduced luminescence of Tb3+ in the low-cost and easy to prepare calcium tungstate. Both the conventional luminescence intensity ratio (LIR) and recently developed single-band ratiometric (SBR) strategies have been achieved in our materials. On the one hand, upon excitation of the charge transfer state, the emissions from the excited 5D4 and 5D3 states present different responses to temperature. A thermometry depending on the LIR between these two emissions has thus been developed, with adjustable relative sensitivity that is sensitive to the excitation wavelength. On the other hand, both the emissions from the excited 5D4 and 5D3 states respond dissimilarly to the temperature variation. A SBR thermometer has thus been constructed with two excitation modes, reaching the maximum relative sensitivity of 1.83% K-1 at 573 K. The present work is expected to inspire other researchers to exploit more multi-mode optical ratiometric thermometries.

Achieving Luminescence of Sr3Ga1.98In0.02Ge4O14:0.03Cr3+ via [In3+] Substitution [Ga3+] and Its Application to NIR pc-LED in Non-Destructive Testing.

Cr3+-doped Sr3Ga2Ge4O14:0.03Cr3+ (SGGO:0.03Cr3+) phosphor was synthesized via a high-temperature solid-phase method. Considering the tunable structure of SGGO, Ga3+ ions in the matrix were substituted with In3+ ions at a certain concentration. The tuned phosphor produced a red-shifted emission spectrum, with its luminescence intensity at 423 K maintained at 63% of that at room temperature; moreover, the internal quantum efficiency increased to 65.60%, and the external quantum efficiency correspondingly increased to 21.94%. On this basis, SGIGO:0.03Cr3+ was encapsulated into a pc-LED, which was applied in non-destructive testing (NDT) experiments, successfully realizing the recognition of water and anhydrous ethanol, proving its potential application in the field of NDT.

Eu3+-based dual-excitation single-emission luminescent ratiometric thermometry.

Recently, single-band ratiometric (SBR) thermometry becomes a hot-spot in the research field of optical thermometry. Here we propose a new SBR thermometry by combining the temperature-induced red shift of charge transfer state (CTS) of W-O and Eu-O with the ground state absorption (GSA) and excited state absorption (ESA) of Eu3+. The emitting intensity of the 5D0-7F2 transition of Eu3+ is monitored under CTS, GSA and ESA excitations at different temperatures. It is found that the SBR thermometry, depending on the combination of [GSA + CTS] of Eu3+ doped calcium tungstate, has the highest relative sensitivity of 1.25% K-1 at 573 K, higher than conventional luminescent ratiometric thermometry such as the 2H11/2 and 4S3/2 thermally coupled states of Er3+.

Efficient near-infrared broadband garnet phosphor for pc-LED and its application to vascular visualization and night vision.

Ultra-broadband near-infrared (NIR) spectroscopy has unparalleled application prospects in intelligent detection and phosphor-converted light-emitting diodes (pc-LED), which are most likely to become the next generation of NIR light sources, has become a hot spot for research nowadays. To cope with the demand for more NIR spectroscopy applications, more efficient NIR phosphors need to be developed. Here, by screening the subject with a smaller band gap and by screening the suitable ion electronegativity of the lattice position where the Cr3+ is located, and then through the energy transfer, a series of Gd3Zn2GaGe2O12:xCr3+, yYb3+ (GZGG:Cr3+/Yb3+) NIR broadband garnet phosphors were found for the first time. By controlling the energy transfer process, the internal quantum yield (IQY) (54.9%), external quantum yield (EQY) (24.65%), bandwidth (260 nm), and thermal stability (60% at 150 °C) of NIR emission were substantially improved. The obtained phosphors are packaged with blue light chips into pc-LED, which can be applied in different fields such as vascular visualization and night vision.

Ultra-sensitive luminescence ratiometric thermometry from 2E→4A2 transitions of AlTaO4:Cr3.

In recent years, non-contact ratiometric luminescence thermometry has continued to gain popularity among researchers, owing to its compelling features, such as high accuracy, fast response, and convenience. The development of novel optical thermometry with ultrahigh relative sensitivity (Sr) and temperature resolution has become a frontier topic. In this work, we present a novel, to the best of our knowldege, luminescence intensity ratio (LIR) thermometry method that relies on AlTaO4:Cr3+ materials, based on the fact that they possess both anti-Stokes phonon sideband emission and R-line emission at the 2E→4A2 transitions and have been confirmed to follow the Boltzmann distribution. In the temperature range 40-250 K, the emission band of the anti-Stokes phonon sideband shows an upward trend, while the bands of the R-lines show the opposite downward trend. Relying on this fascinating feature, the newly proposed LIR thermometry achieves a maximum relative sensitivity of 8.45%K-1 and a temperature resolution of 0.038 K. Our work is expected to provide guiding insights for optimizing the sensitivity of Cr3+-based LIR thermometers and provide some novel entry points for designing excellent and reliable optical thermometers.

Near-Infrared Broadband ZnTa2O6:Cr3+ Phosphor for pc-LEDs and Its Application to Nondestructive Testing.

Broadband near-infrared (NIR) phosphors are necessary materials for developing portable NIR light sources. Moreover, exploiting an NIR phosphor with a main peak located beyond a wavelength of 900 nm remains a challenge because this spectral range has great potential in biological nondestructive testing and solution testing. In this study, a range of Cr3+-doped ZnTa2O6 (ZTO) phosphors were completely synthesized by a solid-state method, which show broadband Cr3+ emission centered at 935 nm with a large full width at half maximum (FWHM) of 185 nm due to two distorted octahedral sites. A packaged phosphor-converted light-emitting diode (pc-LED) device is used to penetrate a 5-cm-thick chicken breast and identify diverse solutions based on differences in the measured transmission spectra. The results indicate broad application prospects in the field of biological tissue penetration and solution analysis.

Chromium(III)-Doped Phosphors of High-Efficiency Two-Site Occupation Broadband Infrared Emission for Vessel Visualization Applications.

The exploration of efficient broadband near-infrared (NIR) emitting materials is essential to establishing new NIR applications. In this work, an excellent NIR phosphor Mg7Ga2GeO12:Cr3+, with an emission band of 650-1350 nm and a full width at half maximum of 266 nm, was successfully prepared. When Ga3+ ions were replaced by In3+ ions, its emission intensity increased 4 times, and the internal and external quantum efficiency reached 86 and 37%, respectively. A NIR phosphor-converted light-emitting diode (pc-LED) component was made by combining a synthetic Mg7Ga1.84In0.07GeO12:0.09Cr3+ phosphor with a 450 nm blue luminescent chip. The vascular and skeletal distribution on human fingers and the back of the hand can be seen under the display of a commercial NIR camera, indicating that Mg7Ga1.84In0.07GeO12:0.09Cr3+ phosphors have promising applications in the field of the blood vessel and bone visualization.

The high thermal stability of white emitting phosphor Mg2 Y2 Al2 Si2 O12 :Dy3+ ,Eu3+ ,La3+ /Lu3+ for white light emitting diodes.

A series of Mg2 Y2 Al2 Si2 O12 :Dy3+ ,Eu3+ was prepared using a solid-state method, and the phosphor emitted white light by tuning the ratio of Dy3+ /Eu3+ . The effects of La3+ /Lu3+ on the structure and luminescence properties of Mg2 Y2 Al2 Si2 O12 :Dy3+ ,Eu3+ were explored. Under the influence of bond length and twist, the luminescence intensity of the materials increased first and then decreased under excitation with ultraviolet light. The lattice distortion of the trivalent cation La3+ -substituted Mg2 Y2 Al2 Si2 O12 :Dy3+ and Eu3+ phosphors was reduced, the symmetry of polyhedron occupied by the luminescence centre improved, and the thermal stability of the luminescence centre improved to a certain extent. White light emitting diodes (LEDs) were fabricated by combining a 370 nm LED chip and the Mg2 Y2 Al2 Si2 O12 :Dy3+ ,Eu3+ ,La3+ (Mg2 Y2 Al2 Si2 O12 :Dy3+ ,Eu3+ ,Lu3+ ) phosphor. The results showed that Mg2 Y2 Al2 Si2 O12 :Dy3+ ,Eu3+ ,La3+ /Lu3+ may have potential application in the area of white LEDs.

Down-conversion luminescence and temperature sensing characteristics of LaSrGaO4 :Er3.

Erbium(III) ion (Er3+ ) has abundant energy levels that can emit light covering a quite broad wavelength range in many hosts. Here we synthesized LaSrGaO4 :Er3+ phosphors by a high-temperature solid-state method. Upon excitation at the ultraviolet (UV) band, LaSrGaO4 :Er3+ phosphors could emit green, red and near-infrared emission simultaneously. The temperature dependent emission characteristics of the as-prepared samples was then studied and two kinds of luminescent ratiometric thermometry were constructed. The first one is on the basis of two green emission bands that stems from the 2 H11/2 → 4 I15/2 and 4 S3/2 → 4 I15/2 transitions of Er3+ . The intensity ratio between these two emission bands was found to follow well with the Boltzmann distribution, and its maximum relative sensitivity was calculated to be 0.84% K-1 at 299 K. The other one depends on the 4 F9/2 → 4 I15/2 transition of Er3+ and self-luminescence of the host LaSrGaO4 , considering that these two emission lines have different temperature response. The relative sensitivity of this type of luminescence intensity ratio (LIR) thermometry could reach 1.86% K-1 at 299 K, we have successfully developed materials with one of the largest relative sensitivities to date, which provides some basis for the subsequent development of a new type of non-contact temperature sensor.

Structural modulation designed a thermally robust blue-cyan emitting phosphor Y2Mg0.8Sr0.2 Al4SiO12:Eu2+ for the high color rendering index white LEDs.

In this work, the novel, to the best of our knowledge, blue-cyan Y2Mg0.8Sr0.2Al4SiO12:Eu2+ (YM0.8S0.2AS:Eu2+) phosphors were synthesized by the solid-state method. At 150°C, the emission intensity of Y2Mg0.8Sr0.2Al4SiO12:0.005Eu2+ can retain 96.38% of the relative intensity, which means that this phosphor shows high thermal stability. A white light-emitting diode (LED) device is fabricated by combining a 370 nm near ultraviolet LED chip and commercial phosphors (green, (Ba,Sr)2SiO4:Eu; red, CaSiAlN3:Eu). The white LED has an excellent property with the correlated color temperature CCT=5236K and superhigh color rendering index Ra=96.1, which indicates the potential application in white LED fields.

Near-Infrared Emitting Phosphor LaMg0.5(SnGe)0.5O3:Cr3+ for Plant Growth Applications: Crystal Structure, Luminescence, and Thermal Stability.

Corresponding to the absorption curve of plant photosensitive pigment Pfr, near-infrared light has a broad application prospect in plant lighting. In order to explore this plant growth lamp, the novel near-infrared emitting phosphor LaMg0.5Sn0.5O3:Cr3+ was synthesized, which can be efficiently excited by 467 nm blue light. There are two luminescence centers, which were proven by testing the low-temperature spectrum, the excitation spectrum at different wavelengths, and the lifetime decay curve, and the two cell sequence substitution processes were obtained by Rietveld refinements of XRD. By introducing Ge4+, its luminescence intensity has been increased 1.6 times and the intensity at 150 °C remains at almost 80% that at room temperature. Finally, two different kinds of illumination experiments for plant growth were carried out, and the feasibility of the LaMg0.5(SnGe)0.5O3:Cr3+ phosphor for plant growth was confirmed.

Self-Luminescence of Perovskite-Like LaSrGaO4 via Intrinsic Defects and Anomalous Luminescence Analysis of LaSrGaO4:Mn2.

A series of deep red phosphors with perovskite-like oxide LaSrGaO4 as host are synthesized by a high temperature solid state method, and the luminescence properties and mechanisms have been investigated in detail. LaSrGaO4 presents self-luminescence at 722 nm, and it is proved that the self-luminescence comes from two kinds of electronic defects and three kinds of vacancy defects, which are anti-occupation defects La Sr•, strontium gap defects Sr i••, the oxygen interstitial defects O i″, substitution defects Sr La', and strontium vacancy defects V Sr″. In addition, when Mn2+ ions are doped in LaSrGaO4, interestingly, the shape of the emission spectra of LaSrGaO4:Mn2+ is the same as that of LaSrGaO4, and the emission intensities are enhanced greatly. Luminescence of Mn2+ ions has been confirmed by doping Mg2+ into LaSrGaO4 and measuring the lifetimes of host LaSrGaO4, LaSrGaO4:Mg2+, and LaSrGaO4:Mn2+ for comparison. The mechanisms of host self-luminescence and Mn2+ luminescence are discussed by detecting the luminescence centers with the low temperature spectra, calculating the forbidden bandwidth with the diffuse reflectance spectra, and calculating the trap depths with the thermoluminescence spectra and further depicted by establishing the transition model. LaSrGaO4:Mn2+ can emit strong deep red light about 722 nm, so the phosphor will have a good application prospect in the field of plant lighting.

Defect-Induced Enhancement Emission Intensity of Ca4.85(BO3)3F(C4.85BF):0.15Bi3+ by Introducing Cation (Na+, Sr2+, Ba2+) or Anion (Cl-).

Generally, the emission intensity of phosphors can be enhanced by introducing a proper number of defects. To enhance the emission intensity of Ca4.85(BO3)3F(C4.85BF):0.15Bi3+, more Frenkel defects were introduced by Na+, Sr2+, and Ba2+. It is found that the number of Frenkel defects is related to volume and covalence of the crystal, in which the covalence has a greater effect than the volume. Furthermore, the larger the volume of the crystal is, the stronger the covalence of the crystal is, the more Frenkel defects will be produced. The volume of Ca4.85- xSr x(BO3)3F(C4.85- xSr xBF):0.15Bi3+ is larger than that of Ca4.85- xNa x(BO3)3F(C4.85- xNa xBF):0.15Bi3+; however, the covalence of Na+ is similar to that of Sr2+, which leads to the same trap depth ( Eα) and defect density (µg) in the quenching concentration. The results also confirmed that the number of Frenkel defects is mainly influenced by the covalence of crystal. Furthermore, crystal distortion also affects the number of Frenkel defects. C4.85- xSr xBF:0.15Bi3+ and C4.85- xNa xBF:0.15Bi3+ have the same distortion at quenching concentration, which results in the same emission intensity in the quenching concentration. Ca4.85- xBa x(BO3)3F (C4.85- xBa xBF):0.15Bi3+ has a larger volume and stronger covalence; meanwhile, it has deeper trap depth ( Eα) and larger defect density (µg) at the quenching concentration, comparing with C4.85- xSr xBF:0.15Bi3+ and C4.85- xNa xBF:0.15Bi3+. However, the distortion of C4.85- xBa xBF:0.15Bi3+ is in agreement with C4.85- xNa xBF:0.15Bi3+ and C4.85- xSr xBF:0.15Bi3+, which leads to the emission intensity of C4.85- xBa xBF:0.15Bi3+ basically the same as that of C4.85- xNa xBF:0.15Bi3+ and C4.85- xSr xBF:0.15Bi3+ in quenching concentration. And the different rates of distortion result in the different quenching concentrations of C4.85- xNa xBF:0.15Bi3+, C4.85- xSr xBF:0.15Bi3+, and C4.85- xBa xBF:0.15Bi3+. Moreover, for Ca4.85- xMg x(BO3)3F(C4.85- xMg xBF):0.15Bi3+ and Ca4.85(BO3)3F1- yCl y(C4.85BF1- yCl y):0.15Bi3+, there are no Frenkel defects due to weaker covalence and smaller volume of the crystal in C4.85- xMg xBF:0.15Bi3+. However, Frenkel defects can be observed in C4.85BF1- yCl y:0.15Bi3+ due to stronger covalence and larger volume of the crystal, furthermore, and the emission spectra and thermoluminescence spectra of C4.85BF1- yCl y:0.15Bi3+ are similar to those of 0.15Bi3+ doped C4.85- xNa xBF:0.15Bi3+, C4.85- xSr xBF:0.15Bi3+, and C4.85- xBa xBF:0.15Bi3+.

Mechanism of Crystal Structure Transformation and Abnormal Reduction in Ca5- y(BO3)3- x(PO4) xF (CBP xF): yBi3.

Tricoordinated planar triangle (PO4)3- may be formed due to the structural differences between planar triangular (BO3)3- and tetrahedral (PO4)3- when (BO3)3- is gradually substituted by (PO4)3-. This transformation of structure may affect the luminescence properties of phosphor. Therefore, a series of Ca5- y(BO3)3- x(PO4) xF (CBP xF): yBi3+ ( y = 0.05, 0.15; x = 0-3), Ca5- y(PO4)3- X(BO3) XF (CPB XF): yBi3+ ( y = 0.05, 0.15; X = 0-1), Ca4.9(PO4)3F (CPF):0.1Eu3+, Ca4.95(PO4)3F (CPF):0.05Bi3+, and nCaF2/CaCl2 ( n = 0-0.1) are synthesized to explore transformation of the crystal structure on luminescence properties. In CBP xF:0.15Bi3+ ( x = 0-3), (PO4)3- is doped to substitute for (BO3)3-, the position of emission spectra remains unchanged and the emission intensity decreases rapidly with increasing x. The underlying main reason for that is formation of the triangular plane (PO4)3-, which has been verified by performing a series of verification experiments of CPB XF: yBi3+ ( y = 0.5, 0.15; X = 0-1). In CPB XF: yBi3+ ( y = 0.5, 0.15; X = 0-1), (BO3)3- is doped to substitute for (PO4)3-, P-O2 bond breaks and the coordination of (PO4)3- varies from four to three when 0.5 < X < 1; meanwhile, the crystal structure transforms from Ca5(PO4)3F (ICSD-9444) to Ca5(PO4)3F (ISCD-30261), which impedes abnormal reduction from Bi3+ to Bi2+. Furthermore, Bi3+ should non-luminance in the plane triangular (PO4)3-, but luminescence in (BO3)3-. Therefore, the emission intensity starts to increase and the emission position suddenly changes from 553 to 474 nm in CPB XF: yBi3+ ( y = 0.05, 0.15; 0.5 < X < 1). From this, the crystal structures of CBP xF: yBi3+ ( y = 0.05, 0.15; x = 0-3) has been inferred to transform from Ca5(BO3)3F (ISCD-65763) to Ca5(PO4)3F (ISCD-30261), and then to Ca5(PO4)3F (ISCD-9444) with x increasing. Emission position remains unchanged and the emission intensity decreases rapidly in CBP xF: yBi3+ ( y = 0.05, 0.15; x = 0-3) do to formation of the triangular plane (PO4)3-. In addition, the rate of abnormal reduction from Bi3+ to Bi2+ can be improved by reducing the electronegativity of the environment around the activator or increasing the ionization energy of the activator, which has been confirmed by verification experiments of CPF:0.05Bi3+, nCaF2/CaCl2 ( n = 0-0.1), and CPF:0.1Eu3+.

A novel red emitting phosphor LiBaB9 O15 :Sm2+ /Sm3+ , li+ with broad excitation band for white LEDs.

A novel tunable red emitting phosphor LiBaB9 O15 :Sm2+ /Sm3+ , Li+ with broad excitation band was synthesized by a high temperature solid-state method. Luminescence properties were investigated in detail by luminescence, X-ray photoelectron spectroscopy (XPS) spectra and CIE chromaticity coordinates. XPS data confirmed that there were Sm3+ in LiBaB9 O15 :Sm3+ and Sm2+ /Sm3+ in LiBaB9 O15 :Sm2+ /Sm3+ , respectively. Spectral property of LiBaB9 O15 :Sm3+ , LiBaB9 O15 :Sm3+ /Sm2+ and LiBaB9 O15 :Sm2+ , Li+ presented that the excitation band of Sm3+ widened and the excitation band of Sm2+ ranged from 350 to 450 nm. And the red light color is tunable with changing Li+ concentration. The results indicated that LiBaB9 O15 :Sm2+ /Sm3+ , Li+ may be promising red phosphor for white light emitting diodes.

Coexistence phenomenon of Ce3+-Ce4+ and Eu2+-Eu3+ in Ce/Eu co-doped LiBaB9O15 phosphor: luminescence and energy transfer.

Ce/Eu-doped LiBaB9O15 (LBB) samples were prepared via conventional high temperature solid state reactions. The XRD patterns, crystal structures, luminescence properties, and decay times were investigated systematically. Ce3+ ions exist in LBB:xCe3+ that were synthesized in a reducing atmosphere and in an air atmosphere. However, we observed Eu2+ ions in LBB:yEu2+ in a reducing atmosphere and Eu3+ ions in LBB:zEu3+ in an air atmosphere. LBB:0.05Ce3+,yEu2+ phosphors synthesized in a reducing atmosphere only possess Ce3+ and Eu2+ and exhibit a broad excitation band ranging from 350 to 425 nm. A reduction phenomenon of Eu3+ → Eu2+ and coexistence of Ce4+, Ce3+, Eu2+ and Eu3+ were observed when LBB:0.05Ce,wEu phosphors were synthesized in an air atmosphere. There are three processes in LBB:0.05Ce,wEu, i.e., energy transfers from Ce3+ to Eu2+ and from Eu2+ to Eu3+, and metal-metal charge transfer (MMCT) between Ce3+ and Eu3+. Moreover, the MMCT process is dominant in LBB:0.05Ce,wEu due to less efficient energy transfer from Ce3+ to Eu2+. Moreover, the CIE coordinates of LBB:0.05Ce,wEu vary systematically from light blue (0.313, 0.129) to red (0.589, 0.315) for LBB:0.05Ce3+,wEu synthesized in air with the changes in Eu ion concentration. Thus, we can control the color by controlling the synthesis atmospheres.

Single-phase tunable white-light-emitting Sr3 La(PO4)3 : Eu2+, Mn2+ phosphor for white LEDs.

A novel, near-ultraviolet-excited white-light-emitting phosphor Sr3La(PO4)3:Eu2+, Mn2+ was synthesized by the solid-state method. Luminescence properties and the energy transfer mechanism were investigated in detail by photoluminescence spectra and decay curves. With the energy transfer between Eu2+ and Mn2+, a cold white light with chromaticity coordinates of (0.2790, 0.2273), correlated color temperature of 6501 K, Ra of 70, and external quantum efficiency of 35.5% was realized by changing the ratios of Eu2+ and Mn2+ in the Sr3La(PO4)3:Eu2+, Mn2+ phosphors. Resonant energy transfer from Eu2+ to Mn2+ ions has been demonstrated to be a dipole-dipole mechanism in Sr3La(PO4)3. The energy transfer efficiency increases with Mn2+ concentration increasing, and reaches a maximum of 55.6%.

Substituting Different Cations in Tuning of the Photoluminescence in Ba3Ce(PO4)3.

An attempt has been made to explore how the luminescence properties change when rare-earth elements are substituted for different cations in the host. We synthesized Eu(2+)-doped Ba3Ce(PO4)3 via a high-temperature solid-state reaction process, substituting for Ba(2+) and Ce(3+) ions and naming them Ba3Ce(1-x)(PO4)3:xEu(2+) and Ba(3-y)Ce(PO4)3:yEu(2+), respectively. The structure, X-ray diffraction with Rietveld refinements, reflectance spectra, and luminescence characterization of the phosphor are measured to explore the difference of substituting for different ions. In order to explain why all of the emission peaks containing the highest peak and the fitting values of Ba3Ce(1-x)(PO4)3:xEu(2+) are shorter than those of Ba(3-y)Ce(PO4)3:yEu(2+) (when x= y), we built a model by N, which represents the surrounding environment. This mechanism is predicted to be general to Eulytite-type orthophosphates and will be useful in tuning optical and other properties whose structural disorder influences the crystallization and is sensitive to local coordination environments. Substituting different cations in tuning of the red shift, widening of the full width at half-maxima (fwhm), and thermal quenching were also observed.